1. Field of the Invention
The present invention relates to a portable dosing apparatus that is capable of continuously dispensing a solution and varying the dispensing rate.
2. Description of Related Art
Portable drug dispensers that are worn by the patient and for dosing the patient with a drug are needed so that the patient can go about his or her normal daily activities while keeping his symptoms under control. Portable drug dispensers of this type include, for example, the compact peristaltic pump taught in Japanese Patent Publication Laid-Open No. 280763/1990, and the infusion pump taught in Japanese Patent Publication Laid-Open No. 236558/1987.
The peristaltic pump taught in Japanese Patent Publication Laid-Open No. 280763/1990 has a first module that is a pump module containing the injectable solution, and a second module that is a motor module containing both a controller and motor. Both the first and second modules can be installed and removed.
The infusion pump taught in Japanese Patent Publication Laid-Open No. 236558/1987 is an integrated unit, but the speed of the motor that is the source of pump drive power can be set manually, and the dispensing rate is therefore adjustable.
The operating cost of this type of portable dosing apparatus should be low because it is used daily by the patient. It is also necessary to be able to adjust the dosing rate according to the patient""s symptoms.
The dosing rate of the above-noted peristaltic pump, however, is determined by the motor module, and the motor module must therefore be replaced to change the dispensing rate. However, because the motor module is part of the solution delivery path, replacing the motor module to adjust the dispensing rate means that dosing stops temporarily. Plural motor modules must therefore be provided if the dispensing rate is to be adjustable, and the cost therefore rises.
While the dispensing rate is adjustable with the above-noted infusion pump, integration of all components into a single unit means that the entire unit must be replaced when the solution runs out. Dosing is therefore interrupted for a relatively long period of time, and operating cost is high.
Both of the prior art devices described above are also powered by a motor using magnetic flux as the drive power source, thus making the power unit larger and reducing device portability. What""s more, the magnetic field generated by magnetic resonance imaging (MRI) and other magnetic medical devices could cause the power unit to be misoperated.
An object of the present invention is therefore to provide a low cost portable dosing apparatus with an adjustable dispensing rate that is capable of continuous dispensing even while changing the dispensing rate.
A further object of the present invention is to provide a portable dosing apparatus that uses a motor that does not use magnetic flux, as the drive power source, and thereby achieves greater compactness and increased reliability.
To achieve the above objects, a portable dosing apparatus (1) for continuously dosing a body with a solution at a dispensing rate that can be varied comprises, according to the present invention, a tank unit (2) for holding the solution, a pump unit (3) for pumping the solution from the tank unit to the body, and a controller (4) for controlling the pump unit, configured such that the tank unit, pump unit, and controller each being freely connectable and disconnectable.
Thus comprised, the dispensing rate can be changed simply by changing the controller. In other words, because it is not necessary to replace any part of the solution dispensing path in order to change the dispensing rate, the time during which dispensing is interrupted when changing the dispensing rate is extremely short.
Furthermore, it is only necessary to replace the tank unit when the solution runs out. In addition, the relatively high cost but same pump unit is used for a specific period of time. Operating cost is therefore low.
It will also be noted that the portable dosing apparatus of our invention is not limited to use with humans, but can also be used with animals.
Furthermore, by further providing a means for securing the portable dosing apparatus to the body, such as wrist strap 11, the portable dosing apparatus can be easily attached to the body. Such an exemplary means is a strap like that of a wristwatch.
The controller typically comprises a CPU, a reference signal generating circuit for CPU operation, and a ROM for storing a control program. The controller in our invention, however, additionally has a dispensing parameter input means (such as buttons 41b) for externally inputting dispensing parameters, and a display (44) for displaying dispensing parameters so that the controller can control the pump unit according to the dispensing parameters.
It is yet further possible to adjust the dosage, dispensing rate, and other dispensing conditions while confirming the information on a display. It is therefore possible to easily and reliably change the dispensing parameters without replacing the controller.
Yet further preferably, the portable dosing apparatus also has a status information input means (42) for inputting status information indicative of a condition of the body. In this case the controller controls the pump unit according to status information from this status information input means.
If such patient information as the heart rate, blood pressure, blood sugar, is entered, the controller can, using the control program stored to ROM, for example, use the supplied information to control the pump unit. As a result, dosage can be easily optimally adjusted even if a person with specialist knowledge is not present.
The tank unit of this portable dosing apparatus preferably has a solution tank (21) that is expandable for internally storing the solution; and a pressure applying means (23) for applying pressure to the solution tank in a direction reducing an internal volume of the solution tank so as to pressurize the solution.
The pressure applying means (23) can thus pressurize the solution in the solution tank, enabling the solution to flow easily from the solution tank. The load on the pump unit upon dispensing is therefore low, and solution""s backflow is suppressed.
The pump unit preferably has an actuator driven according to a drive signal from the controller; a drive power transfer mechanism (such as gear train 34) for transferring drive power from the actuator; and a pump (33) for pumping solution by means of drive power transferred from the drive power transfer mechanism.
This actuator is preferably an ultrasonic motor (5) or a piezoelectric actuator.
By using a compact ultrasonic motor or piezoelectric actuator with high output per unit volume as the drive source for the pump unit, the size of the pump unit is reduced and the portability of the portable dosing apparatus is improved.
Furthermore, because the ultrasonic motor and piezoelectric actuator are not magnetically driven, there is substantially no chance of misoperation when close to a magnetic device. The reliability of the portable dosing apparatus is thus improved.
Further, the pump unit preferably comprises an actuator driven according to a drive signal from the controller; and a pump (73) for pumping solution rotatively by means of drive power transferred directly from the actuator.
This actuator in this case is again preferably an ultrasonic motor (8) or a piezoelectric actuator (63a).
By using a compact ultrasonic motor or piezoelectric actuator with high output per unit volume as the drive source for the pump unit, the size of the pump unit is reduced and the portability of the portable dosing apparatus is improved.
Furthermore, because the ultrasonic motor and piezoelectric actuator are not magnetically driven, there is substantially no chance of misoperation when close to a magnetic device. The reliability of the portable dosing apparatus is thus improved.
Furthermore, because the ultrasonic motor or piezoelectric actuator directly drive the pump unit, a power transfer mechanism is not needed, and a compact, lightweight pump unit can thus be achieved.
Furthermore, the number of the parts is reduced, thus minimizing the manufacturing cost.
The portable dosing apparatus further preferably comprises an operation detection means (such as rotational distance detector 37) for detecting pump unit operation and outputting a detection signal to the controller.
The reliability of the portable dosing apparatus is yet further improved as a result of the controller controlling the pump unit while monitoring pump unit operation.
Yet further preferably, the portable dosing apparatus additionally has a backflow prevention means (such as ratchet 33e) preventing the pump unit from operating in reverse.
In this case the backflow prevention means significantly lowers the chances that the pump will operate in reverse or the solution backflow will occur. The reliability of the portable dosing apparatus is thus yet further improved.
Yet further preferably, the portable dosing apparatus also has a needle (12) for injecting solution to the body.